171. Excel Sheet Column Number

171. Excel Sheet Column Number (Easy)

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

    A -> 1
    B -> 2
    C -> 3
    ...
    Z -> 26
    AA -> 27
    AB -> 28 
    ...

Example 1:

Input: "A"
Output: 1

Example 2:

Input: "AB"
Output: 28

Example 3:

Input: "ZY"
Output: 701

 

Constraints:

• 1 <= s.length <= 7
• s consists only of uppercase English letters.
• s is between "A" and "FXSHRXW".

Related Topics:
Math

Similar Questions:

• Excel Sheet Column Title (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/excel-sheet-column-number/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int titleToNumber(string s) {
        int ans = 0;
        for (char c : s) ans = ans * 26 + (c - 'A' + 1);
        return ans;
    }
};

Or one liner

// OJ: https://leetcode.com/problems/excel-sheet-column-number/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int titleToNumber(string s) { 
        return accumulate(s.begin(), s.end(), 0, [](int num, char ch) { return num * 26 + (ch - 'A' + 1); }); 
    }
};